Valores de subsidencia reciente (Pioceno-Cuaternario) en el Mar de Alborán mediante análisis de “backstripping”

Abstract

A backstripping analysis is presented for the different scientific ODP wells in the Alboran Sea (Leg 161, Holes 976B, 977A, 978A, and 979A). The study has been performed for the complete Pliocene-to- Quaternary sedimentary sequence, based on the detailed paleontological dataset available in these wells. Logging data together with in-situ determinations of porosity and density have been fitted to obtain robust estimates of the appropriate variables to perform the backstripping study (e.g., porosity, density). The total subsidence pattern shows a remarkable coincidence in all the wells (Y=310-355 m) equivalent to a subsidence rate of 0.06-0.07 mm/y for the last 5.1 Ma. In regions where a significant intra-Pliocene hiatus (2.2-5.0 Ma) occurred, like the Site 976-basement high in the West Alboran Basin or the Alboran Ridge, we infer the existence of a major tectonic pulse with high subsidence rates (2.2-5.0 mm/y) that diminished towards the Quaternary (0.07-0.11 mm/y). According to these results, the estimated stretching factor (b) for this basin is 1.35-1.42